Building structure project 1 report

SCHOOL OF ARCHITECTURE, BUILDING & DESIGN Research Unit for Modern Architecture Studies in Southeast Asia Bachelor of Science (Honours) (Architecture) Building Structures (ARC 2523) Prerequisite: Building Construction 2 (ARC 2213)

Project 1 Fettuccine Truss Bridge

Cheah Teck Wei

0315215

Chew Ung Heng

0315397

Low Yong Ging

0313679

Tan Kai Chong

0314223

Tsang Hao Ren

0315753

Yap Kar Juen

0313737

1

Table of Content

Page Number

1. Introduction

3

2. Methodology

4

3. Introduction of Truss

6

4. Materials & Equipment

10

5. Bridge Testing

15

6. Final Bridge

23

7. Conclusion

32

8. Case Study

33

9. References

65

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1.0 Introduction In a group of 6, we are required to design a roof truss using fettuccini as construction material, then tested for how many loads it can carry. The aim of this project is to develop an understanding of how forces are going on in a building structure, such as the tension and compression force. To achieve that, we are required to conduct a precedent study of a bridge to learn and analyse about how the connections, arrangements, and orientation of its truss members affects the strength of the bridge.

With the research and understanding, we are required to apply them on the design the truss of our bridge.

The requirements of the bridge is to not exceed a maximum weight of 80g and must have a clear span of 350mm. The bridge strength as how much kg of load it can carry will be tested and we are required to analyse the reason of its failure and calculate the efficiency of the bridge using the formula:

1.1 Objectives The objective of this project is to develop our understanding of tension and compressive strength of construction material as well as an understanding of force distribution in a truss.

We are also required to learn and able to calculate the efficiency of the bridge and the forces going on in each member so that we could make changes to the design of the truss. By all the objectives achieved we are produce an outcome of a bridge with high level of aesthetic value using minimal construction material.

1.2 Learning Outcomes At the end of project, we will be equipped with the ability to evaluate, explore and improve the attributes of construction materials. Besides that, we are able to explore and apply understanding of load distribution in a truss such as the identifying the tension and compression members in a truss structure. Lastly, with the understandings we could explore different arrangement of members in a truss structure.

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2.0 Methodology

2.1 Materials Testing & Equipment Preparation

Phase 1 : Strength of material Properties of fettuccine is important in building a bridge so that it can carry the maximum load. Properties of the fettuccine must be analysed before construction because the tensile strength in the fettuccine is considered low.

Phase 2 : Adhesive Adhesive plays a huge role in building the bridge as it connects the fettuccine to form a structure. Therefore the adhesive must be chosen wisely as there are many types of adhesive with different function and characteristics. There are certain types of adhesive, which are suitable for constructing the brigde.

Phase 3 : Model Making Drawings are plotted and printed in 1:1 scale to ensure precision in the model making process. The dimension of the fettuccine must be accurate so that the bridge can be strengthenned as much as possible.

Phase 4 : Experiment Completed models are being placed aside to allow the adhesive to sit on the model before testing. Weight is placed in the middle of intermetidate member to ensure the load distribution is even. The results and problems are being recorded for further improvement.

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2.2 Model Making & Design Development The model is plotted according to scale and printed out, so the model making of the fettuccine bridge is based on the printed dimension.

Requirements • • • • •

To have a clear span of 350mm Not exceeding the weight of 80g Only fettuccine and adhesive allowed in the construction of model The bridge will be tested to fail Workmanship is important as part of aesthetic value

2.3 Bridge’s Efficiency Calculation Efficiency of the bridge is calculated after it is tested to fail by using the formula below Efficiency, E = (Maximum load) Mass of bridge

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3.0 INTRODUCTION OF TRUSS A bridge is generally a structure that connects two places that is unreachable by walking, driving and etc., such as river, cliffs and etc. As people and object pass through a bridge, it has to be structurally load bearing and strong enough to withstand their weight. In order to increase its structural strength, bridge truss is designed.

A bridge with truss is called a truss bridge, which is a load bearing superstructure that is composed of a structure of connected elements forming triangular units. The elements may be stressed from tension, compression forces or sometimes both in response to dynamic loads.

Diagram 2.1 Components in a truss bridge.

Tension and compression force is a happening everywhere in our daily life. The tension is a force that acts to stretch or pull an object whereas the compression is a force that acts to squeeze or push an object.

These forces are applied to bridges as well, and they highly affects and damages the structure of the bridge varying from different weight of loads. Besides these forces, there are also different forces such as lateral wind force.

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It is the designer or engineer’s responsibility to design a structure that is safe for public uses, when the forces that applies on the bridge has exceed its load bearing capability, it goes buckling or snapping.

Buckling happens when the compression force has exceed its load bearing capability whereas snapping happens when tension force exceeds. Different members in the truss bridge experiences different kind of forces, and they will have to determine their structural strength and solve it by using different truss design.

Figure 1 Picture of a bridge buckling.

Figure 2 Picture of a bridge snapping.

The best way to deal with these powerful forces is to either dissipate them or transfer them. With dissipation, the design allows the force to be spread out evenly over a greater area, so that no one spot bears the concentrated brunt of it.

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3.1 INTRODUCTION OF HOWE TRUSS

Howe of Massachusetts licensed the Howe truss design in 1840. It is truly an elaboration on the different kingpost design where by two substantial metal poles are substituted for the vertical timbers.

There are likewise minor departure from this example that add a second corner to corner timber to the first single slanting of the different kingpost and/or another inclining timber running the other way between the vertical poles. A few records show that the Howe outline gave an extension that was more grounded than the allwood structure; thus, it turned into the harbinger of iron scaffolds The design of Howe truss is the opposite to that of Pratt truss in which the diagonal members are slanted in the direction opposite to that of Pratt truss (i.e. slanting away from the middle of bridge span) and as such compressive forces are generated in diagonal members. Hence, it is not economical to use steel members to handle compressive force.

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3.2 INTRODUCTION OF WARREN TRUSS

The Warren Truss was patented by James Warren in 1848. It has been around a while.

It is a standout amongst the most famous bridge design. The Warren Truss uses equilateral triangles to spread out the loads on the bridge. This is against the Neville Truss which utilized isosceles triangles.

The equilateral triangles design is recognized by equal sized members and the ability of some of the diagonals to act in both tension and compression. Interestingly, as a load (such as a car or train) moves across the bridge infrequently the strengths for a part change from compression to tension. This happens particularly to the individuals close to the focal point of the bridge.

A Warren truss is a support structure used as a part of distinctive developments, for supporting a load. These are used extensively in bridges as well as, residential and public works designs. The contiguous triangles that are a characteristic part of the Warren truss, also gives them the name, Triangular Truss. These are not common now since modern bridges are made of be steel box girder, post stressed concrete or cable

Warren Truss

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4.0 MATERIALS AND EQUIPMENT 4.1 Main Material - Fettuccine Investigation has been made to 2 diverse kinds of fettuccine to determine their strength and suitability for model making.

Type of Fettuccine

Observation & Description

1.Arbell

• • • •

Flat Profile Heavy Thin Fragile

2. San Remo

• • • •

Concave Profile Light Thick Strong

Efficiency

1

2

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Glue- Adhesive Materials Investigation on a few sorts of super glue to tried on fettuccine to figure out which one is the most suitable as the glue as far as efficiency for model making Type of glue 1 Dolphin Super Glue

Observation & Description

• • • • •

2 V-Tech 3 seconds glue

• • • •

Efficiency

Fettuccine unstiffen by the glue Creates rigid joints Messy Outcomes Glue joints take long times to dry Joints are not strong once it dry

2

Dry very fast Easy to use High efficiency Joints are very strong after it dry

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4.2 EQUIPMENT

Cutter

Sand Paper

The cutter used to cut the fettuccine in model making and the sand paper use to sand the edges of the components of the bridge to fit perfectly.

S-Hook

Bucket

S hook used to hang the load with the guide of bucket on Fettuccine Bridge consequently all the force connected on one purpose of the bridge.

Weight

Water

Weight and water bottle act as the load to test the strength of Fettuccine Bridge

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Weighing Machine Weighing machine use to weight the mass of Fettuccine Bridge to ensure that is not overweight or exceed the maximum weight over 80g

Strength of Material Fettuccine was the main materials that only can be used for the final submission of model making. For better result, we had done the research and analysis before the model making session.

Properties of Fettuccine The fettuccine that we used during the making of the truss bridge model has the thickness of 1mm and the width of 4mm. It is brittle and thus is stronger under the tension. However, fettuccine has a low compression strength • •

Ultimate tensile strength: 2000 psi Stiffness (young’s Module) E: 10,000,000 ( E= stress/strain )

Glue Technique In order to get better efficiency, we ensured that the fettuccine glued with the proper technique to prevent uneven surface and also the ease of building with modular units.

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4.3 Strength Testing Strength testing on 2 types of fettuccine that we choose according to the efficiency.

Fettuccine also were tested by having 5 layers San Remo

+

+

3 seconds glue Brand Type of glue Kimball Super glue

San Remo

Kimball

+

Kimball

+

3 seconds glue 100g ü

200g ü

Super glue

Super glue 250g ü

300g

350g

San Remo San Remo

3 seconds glue Super Glue 3 seconds glue

ü

ü

ü

ü

ü ü

ü ü

500g

X

X

X

X

X

X

X

X

ü X

ü

450g

X X

Kimball

400g

ü ü

ü ü

ü ü

ü X

Model Making & Design Development Requirement for Fettuccini Bridge: 1.

2.

3.

4.

Maximum bridge weight of 80g Only fettuccini can be used 350mm clear span bridge Bridge will be tested until break

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5.0 BRIDGE TESTING 5.1 FETTUCCINE BRIDGE 1

Total Length: 350mm Clear Span: 310mm Bridge Weight: 40g Load Sustained: 1kg

Efficiency: (!)!

!.!"

= 25%

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Problem 1. Connection between frame and structural components applied stacking method.

2. Structural components too weak due to amount of layer.

3. Frame is intact, problem due to poor craftsmanship.

The Warren Truss is one of the most popular bridge designs and examples of it can be found everywhere in the world. The Warren Truss uses equilateral triangles to spread out the loads on the bridge. This is opposed to the Neville Truss which used isosceles triangles.

The equilateral triangles minimize the forces to only compression and tension.

Interestingly, as a load (such as a car or train) moves across the bridge sometimes the forces for a member switch from compression to tension. In our first design we just used 1 layer of fettuccini to connect all joints and we didn't use the super glue properly for sticking all joints so the bridge broke off with just 1kg of water.

Solution 1. Connection between frame and structural components thickened.

2. Sandwich joining method applied.

3. Length of structure calculated & increased.

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5.2 FETTUCCINE BRIDGE 2

Total Length: 400mm Clear Span: 350mm Bridge Weight: 70g Load Sustained: 4kg Efficiency:

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(4)! = 228% 0.07 Problem 1. Mixture of different brand of fettuccine.

2. Structural components in between frames not added.

3. Left gap between frames, causing frame to collapse.

From the exhortation from the first design of our fettuccini bridge, we found out that Warren Truss Design makes a lot of troubles in the support and joints. So we look for another design (Double Howe Truss), a truss having upper and lower horizontal members, between which are vertical and diagonal members; the vertical members of the web take tension, and the diagonal members are under compression. After the weight test, we found out that the support from on the triangular joints member are stronger than warren truss and the efficiency as well.

The main problem of this design is the gap between the frames, makes the bridge has a lot of week points. And we also strengthen up the middle part with adding more layers of fettuccini beam to give better support but it doesn’t have good result in the end which can only take about 4kg weight. Based on our research, we found out that I-beam helped a lot in supporting weight so we decided to change I-beam as our main support.

Solution 1. Mixture of different brand of fettuccine.

2. Structural components in between frames not added.

3. Left gap between frames, causing frame to collapse.

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5.3 FETTUCCINE BRIDGE 3

Total Length: 420mm Clear Span: 350mm Bridge Weight: 107g Load Sustained: 8kg

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Efficiency: (8)! = 598% 0.107

Problem 1.

2.

3.

4.

Minimum gap between frames.

Slanted structural components were not strong enough.

Weight exceeded.

Weak connecting point of fettuccine.

After the previous failure, we had found out that the orientation of diagonal member of the bridge are arranged in a way that does not contribute much in helping to sustain the load as the main load pressure is exerted in the middle of the bottom cord. We had changed its orientation into the opposite orientation from / to \ where the bottom tip of the diagonal member is attached to the middle of the bottom cord which we think it may help in increasing its structural strength.

In this design, the efficiency of bridge had a huge increase but it is because of the exceeded weight of bridge so it couldn’t be used.

Solution 1. Weight reduced.

2. Changes in joining material.

3. Reduced thickness of frames and structural components.

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5.4 FETTUCCINE BRIDGE 4

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Total Length: 420mm Clear Span: 350mm Bridge Weight: 78g Load Sustained: 5kg Efficiency: (5)! = 320% 0.078 Load Sustained: 5kg Problem 1. Middle structure not strong enough to withstand the weight.

Based on our observation and analysis, we had found that the design of our previous bridge has a high potential of load carrying ability and the main problem is having too much of weight. In order for us to maintain or increase its strength when we reduce the weight of bridge, we had decided to redesign it which having a lower pitched end post, shorter vertical and diagonal members.

It has successfully came out with a lower weight which is appropriate according to our requirement but unfortunately having a lower efficiency and load carrying ability.

The only reason of failure at 5kg is because of the breaking of middle I-beam for the hook, and all other structural members were remained stable. So we can assume that it can possibly weight more than 5kg when it has a stronger middle I-beam.

Solution 1. I-beam amount reduced 2. Increased strength of middle I-beam.

Summary Lastly, the efficiency of our final bridge boost up to 680%. Affected by the good craftsmanship, joints and weight to achieve high efficiency of fettuccini bridge. In the final test of our fettuccini bridge, it’s not fully cracked in the end, only the middle part broken off, we found out that the glue which stick the I-beam to the truss in the middle is not strong enough and became the main breaking point. In addition, we finished our final model 3 hours before the final testing to reduce the chemical side effect of superglue.

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6.0 FINAL BRIDGE FINAL MODEL After a few attempts in designing our bridge, we had chosen the fettuccini bridge design 5 as our final model to be tested as it has the highest load carrying efficiency.

The same design and construction method was used and being constructed in a more aesthetic way such as the joints were perfectly made without roughness.

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6.1 FINAL MODEL MAKING STEPS In order to construct our bridge in a more effective way, we had planned steps to construct our bridge.

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Step 1. Both of the base I-beam which is the bottom cord will be constructed.

Step 2. Both of the bottom cord will be connected together by using floor beams. The vertical members will be constructed and glued according to its position with the edge cut bevelled.

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Step 3. The end post will be constructed creating a triangular form.

Step 4. Top lateral bracing is then added.

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Step 5. The diagonal members will be added in between the vertical members. Struts will be added connecting both of the end post.

Step 6. Extra I-beam will be added to the middle member to create a platform for hanging of hook.

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6.2 Joint Analysis (side view) Joint 1 The top part of the bridge is connected to the bottom cord by using a vertical member that is cut and shaved until it is perfectly fits. This is to ensure a larger contact surface that sticks and connects both posts to create a stronger bond. It is tested that perfect fit joints holds more weight compared to just joining the fettuccine by sticking by the side using super glue. Perfect fits makes the entire structure more solid.

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2 Joint 2 The diagonal members are also cut into perfect fit to join in the structure, filling in the blank space and helps to maintain weight. It acts as a member that makes the whole trangular structure rigid. However, it is tested that the diagonal members are not so effective in the structure. It adds more weight into the structure rather than efficiency.

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6.2.1 Joint Analysis (top view) Joint 3 The fettuccine block is fit into the I-beam perfectly to ensure the solidity of the structure. The structure is a lot more stronger while the joints are perfectly cut and fit.

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4 Joint 4 Stacking method is used on the I-beams at the center of the entire structure. This is to ensure balance load distribution of the structure. It is the most important part of the structure because it acts as the haging spot for the weight testing. It has to be strong enough to sustain as much weight as possible.

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Final Bridge Testing and Load Analysis

Figure 3The bridge when it is testing.

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Final test analysis and conclusion In our final model for submission, we managed to carry a 7kg weight by using our bridge which is 72g producing 680% efficiency. It was a great success as it has a higher efficiency value with a lower weight that our last bridge.

However, the broken part is still the middle I-beam which we found out it was because that the super glue that we used to stick it was not strong enough cause by the rain water while we bring it to final testing area. It also caused the drying glue to reduce its adhesive strength and it became the weak point of the whole structure.

FINAL BRIDGE DATA Total Length: 420mm Clear Span: 350mm Bridge Weight: 72g Load Sustained: 7kg Efficiency: (7)! = 680% 0.072 The final result has not met our expectations as it should probably carry more load that 7kg if the structure was not being exposed to rain. Â

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7. CONCLUSION

Final testing model bridge Throughout the project, we had constructed a total number of 6 fettuccine bridges including the final test model. All of them were being experimented for its efficiency in the maximum load it can hold and from each of the breaking and failure, we learnt something and make changes gradually.

This project made us more comprehend load distribution in a structure more profound as we are able to calculate the type of force applying in each structure member.

Before we had our final test model, we investigated diverse course of action of basic individuals and acknowledged it is key to recognize the power (Tension/Compression/Zero/Critical ) in basic individuals so as to accomplish a high productive scaffold outline.

In the conclusion, we learnt how significance of legitimate arranging, as far as work designation and the time interim between culmination of scaffold and load testing. It is because of the proficiency of finishing the scaffold on time and giving a satisfactory time for the glue to dry out and keep up its quality until burden testing.

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8.0 Case Study Case Study 1 (Tsang Hao Ren 0315753)

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Case Study 2 (Yap Kar Juen 0313737)

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Case Study 3 (Tan Kai Chong 0314223)

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Case Study 4 (Chew Ung Heng 0315397)

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Case Study 5 (Low Yong Ging 0313679)

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Case Study 6 (Cheah Teck Wei 0315215)

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9.0 REFFERENCE 1. http://www.garrettsbridges.com/design/howe-truss/ 2. http://www.past-inc.org/historic-bridges/image-howetruss.html 3. http://sydney-harbour-bridge.bos.nsw.edu.au/engineering-studies/warrentruss.php 4. http://www.garrettsbridges.com/design/warren-truss/ 5. https://www.google.com/search?q=HOWE+TRUSS&client=safari&rls=en&s ource=lnms&tbm=isch&sa=X&ved=0CAcQ_AUoAWoVChMIorOcw7C7yA IVy22OCh1pLAWW&biw=1380&bih=762 6. https://www.google.com/search?q=warren+truss+bridge&client=safari&rls=e n&source=lnms&tbm=isch&sa=X&ved=0CAgQ_AUoAmoVChMIdrqyLC7yAIVQhyOCh06GQSs&biw=1380&bih=762

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